The following cmdlets can be used to measure if the switch parameter is working as expected.
Get-QADUser <username> | Get-Member | Where-Object {$_.MemberType -eq "Property" -or $_.MemberType -eq "NoteProperty" -or $_.MemberType -eq "ParameterizedProperty"} | Measure-Object
Get-QADUser <username> -DontUseDefaultIncludedProperties | Get-Member | Where-Object {$_.MemberType -eq "Property" -or $_.MemberType -eq "NoteProperty" -or $_.MemberType -eq "ParameterizedProperty"} | Measure-Object